Renewable Energy Grid Integration: Challenges and Key Issues

Transcription

1 GREENING THE GRID Renewable Energy Grid Integration: Challenges and Key Issues Jaquelin Cochran, Ph.D. National Renewable Energy Laboratory 16 June 2015 ENHANCING CAPACITY FOR LOW EMISSION DEVELOPMENT STRATEGIES (EC-LEDS)

2 Percentage of Electricity Generation A high RE future is achievable Electricity Generation Mix in Scenario Year Wave, Tidal Geothermal Solar (CSP) Solar (PV) Wind, offshore Wind, onshore Bioenergy Hydro Coal, Natural Gas, Nuclear Cochran, Mai, and Bazilian (2014)

3 exceed 50%, belying concerns about [4] Milligan, M.; Porter K.; DeMeo, E.; Denholm, Many countries have already integrated high levels of variable RE D: MYTHS AND MISPERCEPTIONS Country % Electricity from Wind Balancing Denmark 39% in 2014 Portugal 25% in 2013 Interconnection, f exible generation (including CHP), and good markets Interconnection to Spain, gas, hydro, and good market Spain 21% in 2013 Gas, hydro, and good market Ireland 18% in 2013 Gas and good market ty Figure 2. Wind penetration levels in select countries. Many countries have already integrated high levels of VRE. [Sources: Denmark: The Local. (2015). Danish wind energy has record year. The Local Denmark, Science and Technology. January 6, Others: REN21. Renewables Their experiences demonstrate that actions taken to integrate wind and 2014: Global Status Report. (2014). Paris, France: REN21] solar are unique to each system, but do follow broad principles

4 Achieving power systems with high RE requires an evolution in power system planning Wind and solar generation are variable, uncertain, and location-constrained raising new considerations for grid planning and operations 1. Balancing requires more flexibility 2. More reserves 3. More transmission, better planning needed 4. Grid services (e.g., inertia response) from wind/solar or other equipment come at added cost 5. Existing conventional generators needed, but run less, affecting cost recovery

5 Flexibility can help address the grid integration challenges Flexibility: The ability of a power system to respond to change in demand and supply Increases in variable generation on a system increase the variability of the net load Net load is the demand that must be supplied by conventional generation if all RE is used High flexibility implies the system can respond quickly to changes in net load.

6 How much variable RE can power systems handle? Technically: No limit Technological fixes exist for voltage and frequency stability, but at a cost. Economically: Limit = point at which additional variable RE is no longer economically desirable. Benefit-cost ratio can reflect a variety of inputs: Avoided energy costs, carbon pricing Benefits of energy security Costs of technological fixes (e.g., new transmission) This limit is not fixed but can change over time. For example, technology costs can drop, carbon policies can make RE more competitive NREL PIX 20689

7 Frequently Used Options to Increase Flexibility Low capital cost options, but may require significant changes to the institutional context

8 Faster Scheduling to Reduce Expensive Reserves System Operations Hourly schedules and interchanges Sub-hourly scheduling Dispatch decisions closer to real-time (e.g., intraday scheduling adjustments; short gate closure) reduce uncertainty. Source: NREL

9 Output Normalized to Mean Turbines Stdev = 1.21, Stdev/Mean = Turbines Stdev = 14.89, Stdev/Mean = Turbines Stdev = 15.63, Stdev/Mean =.125 Expand Balancing Footprint Broader balancing areas and geographic diversity can reduce variability and need for reserves System Operations 200 Turbines 15 Turbines Seconds x10 3 Source: NREL Wind Plant Data (Approximately Source: 8 NREL hours) wind plant data Approximately 8 hours

10 Increase Thermal Plant Cycling Flexible Generation 0% wind and solar 33% wind and solar energy penetration Generation dispatch for challenging spring week in the U.S. portion of WECC Source: WWSIS Phase 2 (2013)

11 Key Takeaways Wind and solar generation increase variability and uncertainty A wide variety of systems worldwide show 10%+ annual RE penetrations achievable There are no technical limits: investments in flexibility and transmission will enable higher penetration levels of RE Often the most cost effective changes to the power system are institutional (changes to system operations and market designs) Specific back-up generation is not NREL/PIX 10926

12 Thank You! greeningthegrid.org